1. Field of the Invention
The present invention relates to a device which uses a fluidized bed for sorting bodies having different densities, such as, in particular, seeds.
2. Description of the Prior Art
It is known, when it is wanted to separate or sort products having different densities, to use devices in which several physical parameters act on the separation; all such devices are essentially based on the same principle and are mainly constituted by:
PERFORATED GRATES, ON WHICH THE PRODUCTS TO BE SORTED ARE DISPOSED, SAID GRATES BEING SUBJECTED TO A VIBRATION,
A SUCTION SYSTEM DISPOSED ABOVE THE GRATE, OR A BLOWER SYSTEM DISPOSED UNDER THE GRATE.
The grates are inclined to the horizontal, frequently in a longitudinal direction, or sometimes in a transverse direction.
Said known devices have many drawbacks, and are only able to sort properly such products which differ greatly from each other in density. For instance, they allow suitably separating the shelled sunflower seeds from the shells, owing to the fact that the latter are very light and can be removed easily. On the other hand, these known systems are ineffective for sorting, for instance, seeds when it is necessary to separate:
THE SHELLS (THE DENSITY OF WHICH IS CLOSE TO THAT OF THE FRUITS),
THE SHELLED FRUITS, AND
THE UNSHELLED SEEDS.
Since a few years, it is also known to use fluidized bed systems for separating the products as a function of their densitites. This procedure is being used, in particular, for coal-sorting.
According to said method, a thin layer of particles is disposed on a gas-permeable support, and an upward gas stream is caused to pass through said support and said layer, which results in the layer of particles being fluidized. The products to be sorted are poured in the bed thus obtained.
These latter systems have many drawbacks, and up to now it has not been possible to use them in industries such as that of the oil seeds, as the technical problems for working out such systems are very complex if it is wanted to maintain a fluidized bed which is stable with time and has a substantial height.